Malaysia’s authorities must immediately halt the execution of a Nigerian national suffering from mental health problems, convicted of a murder committed around 18 years ago, said Amnesty International.

Osariakhi Ernest Obayangbon is due to be executed on Friday 14 March at 6am local time (Thursday 13 March at 10pm GMT). He was diagnosed as suffering from schizophrenia before his appeal in 2007 and has been receiving treatment for his mental health condition since then. He is currently being detained in Kajang Prison in Selangor state.

“Malaysia’s authorities must immediately stop the execution of Osariakhi Ernest Obayangbon. According to international standards, the death penalty should not be imposed against people with mental disability,” said Hazel Galang-Folli, Amnesty International’s Malaysia researcher.

“Defying international standards to execute a person suffering from mental health problems is just shameful. What makes this case even more shocking is that there has actually been some progress on the death penalty in Malaysia in recent years, with moves to review mandatory death sentencing.”

“There is no evidence that the death penalty is an effective deterrent against crimes. It is absurd to think it can have any such an impact in a case where the person convicted is mentally ill.”

Amnesty International also has serious concerns over whether or not Osariakhi Ernest Obyangbon, also known to Malaysian courts as the British national Philip Michael, based on a passport found in his possession upon his arrest, received a fair trial. A co-defendant facing trial alongside Osariakhi Ernest Obyangbon had his conviction overturned on appeal. Osariakhi Ernest Obyangbon himself did not appeal for clemency, apparently as a result of his mental illness.

More than 50 per cent of those sentenced to death in Malaysia in 2013 are foreigners. Many have been sentenced to death for crimes that do not meet the threshold of the “most serious crimes” under international law.

Malaysia carries out executions in near total secrecy. Transparency on the use of the death penalty is an essential safeguard allowing for appeals and due process to be followed.

Amnesty International opposes the death penalty in all cases without exception. The organization is calling on Malaysia to end all executions, commute existing death sentences and place a moratorium on its use of as first step towards abolition.

Next week, the UN Human rights Council will publish its report on Malaysia’s human rights record. The Malaysian government has so far rejected all recommendations from the international community relating to the abolition of the death penalty, moratorium on executions and commutation of all death sentences to terms of imprisonment.

This is the second planned execution in Malaysia in recent months. In February 2014, Chandran Paskaran faced being hanged for killing another man in a fight. His execution has been temporarily postponed after a public outcry over the case.